Patek Philippe Perpetual Calendar GAS Line is housed in a 30mm

is housed in a 30mm stainless steel case with a sapphire crystal

and the aesthetic is both traditional and a little exciting as well

and a letter from Thierry Stern to the original owner

surpassing watches of their rivals at competitions

Featuring applied indices

Patek Philippe Perpetual Calendar GAS Line is housed in a 30mmA perpetual calendar is like a small computer on your wrist. Think of it this way: Imagine a watch that keeps track of not only the time, but also the date, the day of the week, and the month, and also tells you whether its a leap year or not, and what the current phase of the moon is. Oh, and one more thing imagine it does all of this mechanically, using springs and gears, and that you only have to adjust it once every century or so. Crazy, right?